Tooth point assembly for earth digging structures



TOOTH POINT ASSEMBLY FOR EARTH DIGGING STRUCTURES Filed Feb. 17, 1966 G. E. STEIL Sept. 29, 1970 2 Sheets-Sheet 1 #622 for: Gore/02? Z Ste 28 Mfg), aw

3,530,601 TOOTH PIONT ASSEMBLY FOR EARTH DIGGING STRUCTURES Filed Feb. 17, 1966 G. E. STEIL Sept. 29, 1970 2 Sheets-Sheet 8 United States Patent 3,530,601 TOOTH POINT ASSEMBLY FOR EARTH DIGGING STRUCTURES Gordon E. Steil, River Forest, Ill., assignor to Page Engineering Company, a corporation of Illinois Filed Feb. 17, 1966, Ser. No. 540,429 Int. Cl. E02f 9/28 U.S. Cl. 37142 6 Claims ABSTRACT OF THE DISCLOSURE A tooth point assembly for excavating equipment including a base having a nose portion on which a replaceable tooth point is received and a tooth point having a rearwardly facing cavity for telescoping over the nose of the base characterized in that the base has a pair of forwardly projecting stubs which comprise the nose portion, the stubs having diametrically opposed contacting surfaces generally inclined relative to the major and minor axes of the base and the tooth point cavity has generally mating contacting surfaces so that when the tooth point is driven on the base, the stubs of the base nose are sprung inwardly and the tooth point is secured thereto by the tension exerted on the stubs by the interior cavity of the tooth point.

This invention relates to digging apparatuses and more particularly to a new and improved tooth point assembly for use with earth digging equipment.

In the broad field of earth digging equipment, including dragline excavating machinery, back-hoeing equipment and the like, the portion of the equipment which is intended to attack the earth being excavated, dug, or ripped, is generally provided with some sort of a suitably formed leading edge including a plurality of teeth which are positioned to initially bite into and loosen the earth being attacked. Typically the teeth are part of a tooth point assembly which includes a base intended to be semi-permanently attached to the leading edge of the structure and a tooth point which is detachably secured to the tooth base for removal and replacement responsive to wear.

One of the factors which contributes substantially to tooth point wear is that, although there have been numerous efforts made in the art, heretofore there has not been a satisfactory structural arrangement developed for secur ing the tooth point on the tooth base in such a manner as to eliminate substantially all movement of the tooth point relative to the tooth base during the digging operation. In all of the previously known tooth assembly structures, movement of the point relative to the base in at least one plane has been possible during the digging operation. This relative movement is a substantial factor in contributing to the erosion, wear, and often premature breakage of the tooth structure. Therefore, this invention is directed to the provision of a tooth point assembly wherein the point is secured to the base in such a fashion as to eliminate movement of the point relative to the base and permit only axial withdrawal of the point from the base for replacement purposes, thereby significantly increasing tooth point life.

It is therefore a general object of this invention to provide a new and improved tooth point assembly for use with earth digging equipment.

It is a primary object of this invention to provide a new and improved tooth point assembly for earth digging equipment wherein the point and base are constructed and arranged so that the point is secured on the base in such a manner as to generally eliminate relative movement between the point and the base.

Another object of this invention is to provide a new 3,530,601 Patented Sept. 29, 1970 and improved tooth point assembly wherein the tooth base and point have complementary structure so that when the point is assembled on the base, portions of the base received in the point are sprung during assembly and held in a sprung position by hoop tension afforded by the structure of the tooth point to eliminate movement of the point relative to the base.

Another object of this invention is to provide a new and improved tooth point assembly for earth digging equipment wherein the tooth base and tooth point are provided with mating contacting surfaces which are formed in diametrically opposed quadrants that lie between the longitudinal and vertical axes of the tooth point assembly.

A further object of this invention is to provide a new and improved tooth point assembly for earth digging equipment wherein the tooth point cavity is provided with filleted corners which urge the contact surfaces of the tooth base to be sprung inwardly and which form part of the hoop exerting hoop tension on the base contact surfaces.

Yet another object of this invention is to provide a new and improved tooth point assembly wherein the mating contact surfaces of the tooth base and tooth cavity are segments of the surfaces of imaginary intersecting cylinders.

Still a further object of this invention is to provide a new and improved tooth point assembly wherein the tooth base and tooth point contacting surfaces are generally arcuate, taper inwardly in a converging fashion toward each other, and also taper downwardly and outwardly in a generally lateral direction.

Another object of this invention is to provide a new and improved tooth point assembly including a base having outwardly projecting stubs with opposed contacting surfaces and a tooth point provided with a cavity having mating contacting surfaces, the contacting surfaces of the point and base being segments of the surfaces of intersecting cylinders, the corner portions of the tooth point cavity being filleted so that the inner Walls of the cavity form a hoop, and the cavity having a depth greater than the length of the projecting stubs so that the tooth point can be telescoped over the tooth base with the mating contacting surfaces forced axially past each other responsive to endwise driving of the point relative to the base thereby causing the stubs to be sprung slightly inwardly towards each other and held in a sprung position by the hoop tension afforded by the inner walls of the tooth point cavity so that movement of the point relative to the base is substantially eliminated.

Other objects, features and advantages of the present invention will be apparent from the following description of the preferred embodiments illustrated in the accompanying drawings, in which:

FIG. 1 is a fragmentary side elevational view showing a dragline excavating bucket with which the tooth point assembly of this invention may be used;

FIG. 2 is a side elevational view of the tooth point assembly of this invention;

FIG. 3 is a top plan view of the tooth point assembly of this invention;

FIG. 4 is a section view taken along the lines 4-4 of FIG. 3 showing the relationship of the base member and point of the tooth point assembly of this invention;

FIG. 5 is an exploded view of the tooth point assembly of this invention;

FIG. 6 is a front elevational view of the base member of the tooth point assembly of this invention; and

FIG. 7 is a rear elevational view of the tooth point member of the tooth point assembly of this invention.

The tooth point assembly of this invention may be utilized with suitable excavating or earth digging apparatus such as dragline excavating bucket controlled by lift lines 12, pull lines 14, and dump lines 16 for excavating a load 18 from the earth 20. This load may be surface soil, rock or subsoil matters such as coal or the like. Typically such earth digging structure has an earth engaging leading edge portion such as a forward lip 22 on which teeth, such as tooth point assembly 24 of this invention, may be secured to aid in cutting material being dug as the bucket is forced through the earth, such as by pulling on pull line 14.

In normal operation, the bucket teeth are subjected to extremely severe forces and engage highly abrasive material. For this reason, the excavating buckets are generally made of heavy steel and tooth points are made of heavy steel or similar material.

The tooth point assembly 24 of this invention includes a base member 26 and a point member 28 which is de tachably secured to the base. Typically in tooth point assemblies, the base member is permanently mounted on the digging structure, such as the bucket lip, by means such as welding, and the point is removably attached to the base for replacement responsive to wear and the like. For purposes of securing the tooth point assembly to the digging apparatus, the base 26 is provided with suitable structure such as the generally rearwardly extending forked bifurcation 30 which is constructed and arranged to embrace the forward portion of the lip 22 of the dragline excavating bucket 10 so as to be easily secured by welding or the like. This generally bifurcated construction 30 is typical of structure well-known and old in the art for facilitating assembly of the tooth base on the lip of an excavating structure. It is also possible that the base 24 could be formed as part of an integrally cast bucket lip.

The base is provided with a generally fiat transverse face 32 on which are formed means for receiving the tooth point in the form of a nose portion comprising a pair of laterally spaced stubs 34 projecting outwardly from the face in a generally forwardly converging configuration. Preferably each of the stubs is symmetrical with relationship to a plane extending generally transversely of the stubs and perpendicularly to face 32. The lateral extent of each of these stubs is defined by a generally trapezoidal-shaped inside wall 36 and generally trapezoidal-shaped outsidewall 38. The space between the inside walls 36 may be partially filled and could accommodate a fastening means different from the J-bolt fastener shown in the drawings and to be described in detail later. The inside walls have a greater transverse dimension throughout their length (or a greater dimension in a plane generally parallel to the face 32) than the outside walls 38. The inside walls 36 project generally perpendicularly outwardly relative to face 32, but the outside walls 38 taper slightly inwardly toward inside walls 34.

The opposed or upper and lower surfaces of each stub 34 are provided with contact or bearing surfaces and 42, respectively, which are intended for facial contact with mating surfaces in the tooth point. 'Each set of upper and lower contact surfaces 40 and 42 on each stub 34 generally forwardly converge towards each other in a direction away from face 32. The lateral extent of con tact surfaces 40 lies generally between the area indicated by 40a and 40b and the lateral extent of contact surfaces 42 lies generally between the area defined by 42a and 42b.

That portion of each of the stubs between contact surface. 40' and inside wall 34 is connected by a rounded surface 44b, and that portion of each of the stubs between contact surface 40 and side wall 38 is connected by a rounded portion 44a. Similarly, that portion of each of the stubs between side wall 38 and contact surface 42 is connected by rounded surface 46a and that portion of each of the stubs between contact surface 42 and inside wall 36 is connected by rounded surface 46b. The

4 stubs terminate in a generally flat face 48 which is substantially parallel to face 32. As will be explained, it is intended that the longitudinal extent of the stubs will be such as to keep the fiat ends 48 out of contact from the end of the tooth cavity.

Tooth point member 28 has an external digging configuration defined by a forward blade-like portion 54, preferably formed at an angle approximately 26 to 30 degrees to initially bite into and cut the earth being attacked by the earth digging apparatus to which the point assembly of the invention is attached. The point has a rearward, outwardly diverging portion 56 terminating in a generally planar rear end 58 having an enlarged opening 59 extending into cavity 60 in the interior of the tooth point. Cavity 60 tapers in a generally converging manner towards the forward blade portion 54 and terminates in a generally upright forward end cavity Wall 62. Preferably wall 62 is formed substantially parallel to the end wall 58. It has been found that an ideal ratio between the length of the cavity 60 and the direction of the longitudinal extent of the tooth point is in a ratio of approximately 1:2 with relationship to the overall length of the tooth point.

The interior of cavity 60 is defined by side walls 64 which are substantially parallel, tapering only slightly forwardly from face 58, and have a generally converging configuration towards end wall 62 commensurate with the general taper of a tooth point. Tooth point cavity 60 is provided with opposed upper and lower walls 66 and 68, each of which has contact surfaces 66a and 68a, respectively, for generally mating in facial contact with contact surfaces 40 and 42, respectively, of the stubs 34.

The area between side walls 64 and contact surfaces 66a filleted as at 70 and 72 in a configuration approximating a portion of a surface of a cone, as are the areas between side walls 64 and contact surfaces 68a. One problem which has been frequently encountered in tooth point assembly constructions is that generally such tooth point assemblies have generally rectangular cross sectional configurations with angular corners, resulting in stress concentrations in the corners. Corner breaks in tooth points have become a common occurrence. The corner fillets 70 and 72 of the tooth point of this invention are formed on a relatively large radius to avoid the stress concentration and also permit a continuous hoop tension to be applied by the inner walls of the cavity .60. For example, where the radius of the surfaces defining the tops and bottoms of the cavities 66 and 68, respectively, is approximately 10 inches, a corner radius for the areas 70 and 72 of 1 /2 inches has been found to be suitable. Preferably, the ratio of the radius of the surfaces to the overall width of the point, for example, the ratio of the radius of the surfaces forming walls 66 and 68, is 1% 1. This aforementioned radius serves to aid in maintaining the configuration of the tooth point generally within 30 degrees by keeping the tooth thickness at a minimum from top to bottom.

In keeping with the desirability of maintaining a 30- degree or less angle between the top and bottom of the exterior of the tooth point, the included angle between the top and bottoms of the stub and the included angle generally defining the tops and bottoms of the tooth point cavity is preferably between 26 and 28 degrees.

A forwardly to rearwardly extending rib 74 is formed in cavity 60 and is provided with a transversely extending opening 76 for receiving the head of a J-bolt 78. J-bolt 78 is intended to project through an opening 80 formed in the tooth point base so that the threaded end 82 of J-bolt 78 may have a nut secured thereon to retain the tooth point on the base against axial dislodgement upon initial assembly of the tooth point onto the base.

In the preferred embodiment, the contact or bearing surfaces 40, 42, 66a and 68a are arcuate, being segments of the surfaces of imaginary intersecting cylinders. For example, surfaces 66a and surfaces 40 would also lie on the surface of a cylinder which intersects faces 32 and 58 and is canted downwardly relative thereto whereas surfaces 42 and 68a would lie within the surface of a substantially identical cylinder which intersects faces 32 or 50, respectively, and is canted upwardly relative thereto. With regard to the major or longitudinal axis A and vertical or minor axis B (FIGS. 6 and 7) of the tooth point and the base, these aforementioned contacting or bearing surfaces face generally outwardly in diametrically opposed quadrants which lie between these axes. Thus a plane generally perpendicular to the general extent of each of the aforementioned bearing surfaces would intersect both the longitudinal and vertical axes of the point and base and would be diagrammatically illustrative of the outwardly diverging nature of the forces involved in the mating engagement of the tooth point and base. Where the aforementioned bearing and contacting surfaces are arcuate, as is the case with the preferred embodiment, such a plane would actually be perpendicular to a chord of these surfaces; but this plane would be perpendicular to the surfaces in the event that the contacting surfaces were planar instead of arcuate.

As previously mentioned, the filleted corners 70 of the tooth point define segments of the surface of a cone and thus these corners are of greater extent near the base 58 than adjacent end wall 62. The same is generally true of the rounded corner portions 44a and 46a of the stubs, although it is to be understood that the stub rounded corner surfaces are formed on a smaller radius so as to be free of contact of the filleted corners 70 as shown in FIG. 4.

During assembly, the tooth point is telescoped over the stubs and the J-bolt is substantially tightened through the use of nut 84. The end of forward blade portion of the point is then struck with suitable means, such as a sledge hammer or the like, to endwise or axially drive the point further on the base. The stubs 36 are caused to be deflected and sprung slightly inwardly towards each other by the mating engagement with the bearing surfaces or contacting surfaces in the interior of the tooth point and the action of the filleted corners tending to cramp the stubs inwardly. The generally hoop-like configuration of the interior of the tooth point cavity holds the point on the base with the stubs in this deflected position in hoop tension. This tension combined with the outwardly diverging arrangement of the bearing surfaces locks the point on the base against movement except in an axial direction, such as permitted during removal of the point for replacement. The nut is then tightened firmly on the J-bolt so as to safeguard against accidental withdrawal. It has actually been found during use that the point is even further forcefully tightened upon the stubs and conditions have been experienced wherein the point is locked on the base and held during working field condiditions even without the use of a J-bolt to prevent axial withdrawal.

In formation of these assemblies, the tooth point is first cast from a mold in the usual manner. A fiberglass molding material is then poured into the cast point which serves as a mold for making the original pattern for the tooth base directly from the point. After taking the original pattern from the point by the fiberglass mold, slight clearances are shaved along the fiberglass mold in the areas of outside walls 38, and the ends 48 of the stubs are shaved short of the original impression. A sand casting mold is then made from the fiberglass mold to form the pattern for the tooth base and particularly the stub portions thereof. Thus the sand mold made from the fiberglass mold will produce a smoothly cast tooth base which is slightly undersize in the side and end areas relative to the tooth point. This allows the tooth point to be driven on the tooth base so that mating portions of the point and base are slightly axially telescoped past each other to aid in causing the slight spring deflection of the stubs during assembly.

It is to be understood that this structure may be util ized with a replaceable tip as is general practice in the industry. Thus, for example, the forward blade portion 54 could be replaceably connected to the remainder of the point 28 by means utilizing a pin fastening or the like, several such arrangements being 'well known in the art.

The aforementioned contacting surfaces and related fillets and the like should be accurately formed in order to apply the principles of this invention even though the tooth points themselves must be, of necessity, extremely heavy, bulky and durable items. For example, tooth points for use with 45-cubic yard excavating buckets may be approximately 10 inches wide along the cutting edge or blade edge 54. Such points themselves will weigh pounds and the bases approximately 250 pounds so that the total weight of one such tooth point assembly may approximate 400 pounds. Generally five such teeth are used on a bucket of this size. In spite of the heavy mass involved, and the severe blows to which the teeth are subjected in attacking the earth, such as when the excavating bucket with all of its mass is dropped against hard or rocky soil, the structure afforded by the tooth point assembly of this invention insures that the point and base will be locked to each other effectively against movement thereby promoting the wear and life of the assembly.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as some modifications may be obvious to those skilled in the art.

What is claimed is:

1. A tooth point assembly for earth digging structures, comprising: a tooth base having a rearwardly extending bifurcated portion for reception on a forward lip of an earth digging structure, said base having a pair of forwardly extending laterally spaced stubs, each of said stubs having inside walls spaced from each other and outside walls of lesser dimension in transverse section than said inside walls and tapering slightly towards each other in a forwardly extending direction; opposed upper and lower tooth point bearing surfaces on said stubs tapering laterally outwardly between said inside walls and said outside walls, said bearing surfaces also forwardly converging toward each other being arcuate in said lateral direction and of substantially constant width through the length of each stub, the upper bearing surfaces being portions of the surfaces of a first imaginary cylinder and the lower bearing surfaces being portions of the surfaces of a second imaginary cylinder which intersects said first cylinder; a tooth point having a forwardly tapering nose and a rearwardly opening cavity for receiving the tooth base stubs, the depth of said tooth point cavity being slightly greater than the length of said tooth base stubs, said cavity including side walls and opposed upper and lower walls joined to said side 'walls in a rounded juncture to generally define a hoop-like structure in transverse section, said opposed upper and lower walls having contacting surfaces of a mating configuration to said stub bearing surfaces, the base and cavity being assembled together with mating portions of the base and cavity being slightly axially telescoped past each other and the stubs deflected and sprung slightly inwardly toward each other, the tooth point cavity holding the stubs in a deflected sprung position by means of hoop tension thereby preventing movement of the point relative to the base except for axial dislodgment thereof; and means for holding the point on the base against axial withdrawal 2. A tooth point assembly for earth digging structures, comprising: a tooth base having a rearwardly extending portion adapted for securement to an earth digging structure, said base having a forwardly extending nose portion comprising a pair of laterally spaced stubs, each having inside and outside walls and upper and lower contacting surfaces between the inside and outside walls, the inside walls of the stubs having a greater dimension between the upper and lower contacting surfaces than the outside walls in any plane generally normal to the length of the stubs, with contacting surfaces generally tapering therebetween, said nose portion having a major axis lying in a plane extending in a forwardly to rearwardly direction generally parallel to a cutting edge of a tooth point adapted to be mounted thereon and a minor axis lying in a plane extending generally perpendicular thereto, said contacting surfaces generally facing outwardly in diametrically opposed quadrants lying between the major and minor axes of the tooth base and inclined relative to said axes and said planes; a tooth point having a rearwardly facing socket means for receiving the nose portion of the tooth base and a forwardly facing cutting edge, said tooth point having a major axis lying in a plane extending in a forwardly to rearwardly direction generally parallel to the cutting edge and a minor axis lying in a plane extending generally perpendicular thereto, said socket means including contacting surfaces mating with the nose portion contacting surfaces and lying between said planes and said major and minor axes, the tooth point and base being assembled by endwise driving of the point on the base with the nose portion being sprung thereby to a deflected position to hold the point on the base against movement relative to the base by the engagement of the nose portion contacting surfaces with the mating surfaces in the tooth point cavity.

3. The tooth point assembly of claim 2 wherein the contacting surfaces of each stub taper toward each other in a forwardly converging fashion.

4. A tooth point base for use with a replaceable tooth point having a forwardly facing cutting edge and a rearwardly facing cavity, comprising: a member having a rearwardly extending portion constructed and arranged for securement to an earth digging structure, said member having a forwardly extending nose portion for reception in the cavity of a tooth point, said nose portion comprising a pair of laterally spaced stubs, each of the stubs having an outside wall and an inside wall, the inside walls of the stubs being in opposed relationship to each other and of a greater dimension in transverse section through the length of the stubs than the outside walls, with contacting surfaces extending from the inside walls and convergently tapered toward the outside walls, said nose portion having a major axis lying in a plane extending in a forwardly to rearwardly direction and generally parallel to a cutting edge of a tooth to be mounted thereon and a minor axis lying in a plane extending generally perpendicular thereto, said contacting surfaces generally facing outwardly in opposed quadrants lying between the major and minor axes of the nose portion and inclined relative to said axes and said planes.

5. The tooth base of claim 4 wherein the contacting surfaces of each stub also forwardly converge toward each tooth terminating at the forward end of the stubs.

6. The tooth base of claim 5 wherein the contacting surfaces are arcuate being segments of the surfaces of intersecting points.

References Cited UNITED STATES PATENTS 1,485,879 3/1924 Page 37-142 1,959,847 5/1934 Van Buskirk 37142 XR 1,992,591 2/1935 Whisler 37-142 XR 2,108,075 2/1938 Mork 37-142 2,167,425 7/1939 Page 37142 2,256,488 9/1941 Murtaugh 37142 2,311,463 2/1943 Page 37-142 2,397,521 4/1946 Askue 37142 2,740,212 4/ 1956 Werkheiser et al 37142 2,752,702 7/1956 Nelson 37142 2,860,863 11/1958 Bruestle et al. 299-92 XR 2,915,290 12/1959 Petersen 299-91 XR FOREIGN PATENTS 475,279 7/1951 Canada.

EDGAR S. BURR, Primary Examiner U.S. Cl. X.R. 

